SKOS, RDFa, Microformats, Microdata
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Transcript of SKOS, RDFa, Microformats, Microdata
SKOS, RDFa & Co, Linked Data Related Examples
INFO 4302 - April 20, 2011Bernhard Haslhofer - Cornell University
Today we talk about...
• Simple Knowledge Organization System (SKOS)
• Machine-readable data in (X)HTML(5)(RDFa, Microformats, Microdata)
• Search Engines and machine-readable data
• Facebook Graph API & Open Graph Protocol
Linked Data Recap
Why Linked Data?
• There is lots of information on the Web
• ... valuable information that can be (re-)used
• Problem• information is usually expressed in the form of
HTML documents
• the underlying raw data are locked in closed data silos (mostly DBMS)
Why Linked Data?
• The Web is successful because it provides• Uniform encoding (HTML)
• Uniform addressing (URI)
• Uniform transportation (HTTP)
for the exchange of documents.
• Why not apply the same mechanism to the underlying data?
What is Linked Data?
• A method to build a Web of Data
• Architectural style, set of standards
Web
Publishing Data
• Distinguish between non-information and information resource
• Sample non-information resource• http://dbpedia.org/resource/The_Shining_(film)
• Sample information resource• http://dbpedia.org/page/The_Shining_(film) - HTML
• http://dbpedia.org/data/The_Shining_(film) - RDF
Publishing Data
GET http://dbpedia.org/resource/The_Shining_(film)Accept: application/rdf+xml
303 See OtherLocation: http://dbpedia.org/data/The_Shining_(film)
GET http://dbpedia.org/data/The_Shining_(film)Accept: application/rdf+xml
200 OK...<?xml version="1.0" encoding="utf-8"?><rdf:RDF ...
Simple Knowledge Organization System (SKOS)
• A language for describing controlled vocabularies (taxonomies, thesauri, classification schemes)
http://dbpedia.org/resource/The_Shining_(film)
http://dbpedia.org/resource/Category:1980s_horror_films
http://dbpedia.org/resource/Category:1980s_films
http://www.w3.org/2004/02/skos/core#Concept
skos:subject rdf:type
skos:broader
rdf:type
Excursus: The Semantic Spectrum
semanticexpressiveness
complexity
Glossary
Taxonomy
Thesaurus
Data Model
Ontology
Term/Tag list
SKOSXML/S
Folksonomy
UMLER
OWLDL, FOL, etc
Knowledge Organization Systems (KOS)
Glossary
• A simple (alphabetical) list of terms and their definitions for a particular domain of knowledge
• Useful for creating clear and unambiguous term definitions
Folksonomy
• Collaborative tagging systems
• Web 2.0., social-media, etc...
Controlled Vocabulary
• A simple list of terms, definitions and naming conventions
• Some process “controls” adding and removing term definitions to ensure consistency
• Terms are often defined in relationship to each other
• Taxonomies, Thesauri, and Ontologies are special forms of controlled vocabularies
Taxonomy
• Classification of entities in a hierarchy
• A taxonomy node stands for a real-world entity
animate object
agent
organizationperson
manager employee
subclass of
source: http://upload.wikimedia.org/wikipedia/commons/b/bb/Linnaeus_-_Regnum_Animale_%281735%29.png
Thesaurus
• Associates the meaning of a term with the meaning of another term
• hypernym, hyponym, synonym, antonym
Imagery
Aerial imagery Infrared imagery
Radar imagery
Moving target
indicators
Radar
photography
narrower than
Combat support
equipment
Intelligence and electronic
warfare equipment
Imaging systems
Imaging radarInfrared imaging
systemsrelated to
Ontology
• Defines concepts that represent an area of knowledge
• Machine-read and -interpretable representation
• Classes, instances, relationships, properties, functions, constraints, etc.
http://www.bbc.co.uk/ontologies/programmes/2009-09-07.shtml
Simple Knowledge Organization System (SKOS)
What is SKOS?
• A model for expressing the basic structure and content of concept schemes such as thesauri, classification schemes, taxonomies, folksonomies, and other similar types of controlled vocabularies
• Allows concepts to be composed and published as Linked Data on the Web
• Hides the complexity of OWL - easy to use
semanticexpressiveness
complexity
Glossary
Taxonomy
Thesaurus
Data Model
Ontology
Term/Tag list
SKOSXML/S
Folksonomy
UMLER
OWLDL, FOL, etc
SKOS Concepts are...
• ... identified with URIs
• ... labeled with 1..* natural language strings
• ... documented with various types of notes
• ... semantically linked to each other
• ... aggregated into concept schemes
Example SKOS Concept
skos:Concept
• Concepts are• the units of thought: ideas, meanings, categories of
objects, etc.
• abstract entities which are independent of the terms used to label them
lcsh:sh2007025344#concept
skos:Concept
rdf:type
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .@prefix lcsh: <http://id.loc.gov/authorities/> .
skos:(pref|alt|hidden)Label
• Labels refer to concepts’ natural language(s)• skos:prefLabel: the preferred lexical label
• skos:altLabel: alternative lexical labels (e.g., synonyms)
• skos:hiddenLabel: labels useful for indexing
"Parody films"@en
skos:prefLabel
lcsh:sh2007025344#concept "Movie parodies"@enskos:altLabel
"Send-up films"@en
skos:altLabel
SKOS Semantic Relationships
• The meaning of a concept is also defined by its links to other concepts• skos:broader: hierarchical link to a more general concept
• skos:narrower: hierarchical link to a more specific concept
• skos:related: associative (non-hierarchical) link
"Parody films"@enskos:prefLabellcsh:sh2007025344#concept
"Comedy films"@enskos:prefLabellcsh:sh2007025038#concept
skos:broader
skos:broader
skos:narrower
skos:narrower
SKOS Documentary Notes
• Add further human-readable documentation• skos:scopeNote: info about intended meaning
• skos:definition: complete explanation of meaning
• skos:example: example concept use
“This heading is used as a genre/form heading for films that comically imitate another work or group of works of a more serious nature.”@en
skos:scopeNotelcsh:sh2007025038#concept
"Comedy films"@en
skos:prefLabel
skos:ConceptScheme
• Allow the organization of skos:Concepts in some Knowledge Organization Scheme (KOS)
skos:inScheme
skos:Conceptlcsh:sh2007025038#concept
skos:ConceptSchemelcsh:#genreFormTerms
skos:Concept...
skos:inScheme
Example
• Dereference and analyze“Jack Nicholson” @ New York Times
• http://data.nytimes.com
• http://data.nytimes.com/N5761411277431266513
RDFa, Microformats & Microdata
Why RDFa?
GET http://dbpedia.org/resource/The_Shining_(film)Accept: application/rdf+xml
303 See OtherLocation: http://dbpedia.org/data/The_Shining_(film)
GET http://dbpedia.org/data/The_Shining_(film)Accept: application/rdf+xml
200 OK...<?xml version="1.0" encoding="utf-8"?><rdf:RDF ...
Oh dear!
What is RDFa?
• A mechanism for embedding RDF metadata within XHTML 1.1 Web documents
• Defines a set of attributes to augment visual data with machine-readable hints
• User agents can extract triples from RDFa-enables Web pages
What is RDFa?
• Markup human-readable data (HTML) with machine-readable indicators
...All content on this site is licensed under<a href="http://creativecommons.org/licenses/by/3.0/"> a Creative Commons License</a>.
RDFa Example
...All content on this site is licensed under<a rel=”license” href="http://creativecommons.org/licenses/by/3.0/"> a Creative Commons License</a>.
XHTML
XHTML + RDFa
RDFa Attributes
• about and src: the resource the metadata is about
• rel and rev: (reverse) relationship between resources
• href and resource: the partner resource
• property: a property for the content of an element
• content: override content of an element
• datatype: specify the datatype of text
• typeof: specifies the RDF type(s) or a subject
<div> <h2>The trouble with Bob</h2> <h3>Alice</h3> ...</div>
RDFa Example
<div xmlns:dc="http://purl.org/dc/elements/1.1/"> <h2 property="dc:title">The trouble with Bob</h2> <h3 property="dc:creator">Alice</h3> ...</div>
XHTML
XHTML + RDFa
<div xmlns:dc="http://purl.org/dc/elements/1.1/">! ! ! <div about="/alice/posts/trouble_with_bob"> <h2 property="dc:title">The trouble with Bob</h2> <h3 property="dc:creator">Alice</h3> ... </div>
<div about="/alice/posts/jos_barbecue"> <h2 property="dc:title">Jo's Barbecue</h2> <h3 property="dc:creator">Eve</h3> ... </div>
...
</div>
RDFa Example
XHTML + RDFa
<div typeof="foaf:Person" xmlns:foaf="http://xmlns.com/foaf/0.1/"> <p property="foaf:name"> Alice Birpemswick </p>
<p> Email: <a rel="foaf:mbox" href="mailto:[email protected]">[email protected]</a> </p> <p> Phone: <a rel="foaf:phone" href="tel:+1-617-555-7332">+1 617.555.7332</a> </p></div>
RDFa Example
XHTML + RDFa
RDFa Examples
• OReilly.com: http://oreilly.com/catalog/9780596520694/
• Rottentomatoes: http://www.rottentomatoes.com/m/shining/
Microformats
• A Microformat extends conventional HTML tags with semantic information
• Started by Technorati, Inc.; now community-driven (IRC, mailing list, blogs)
• Make use of the following (X)HTML attributes• class
• rel
<div> <div>Joe Doe</div> <div>Jo</div> <div>The Example Company</div> <div>604-555-1234</div> <a href="http://example.com/">http://example.com/</a> </div>
Microformats Example
<head profile="http://www.w3.org/2006/03/hcard"> ... </head> ... <div class="vcard"> <div class="fn">Joe Doe</div> <div class="nickname">Jo</div> <div class="org">The Example Company</div> <div class="tel">604-555-1234</div> <a class="url" href="http://example.com/">http://example.com/</a> </div>
HTML
XHTML + Microformats
Microformats Example
Available Microformats
Microformats vs. RDFa
<div xmlns="http://www.w3.org/1999/xhtml" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" xmlns:v="http://www.w3.org/2006/vcard/ns#"> <div about="http://example.com/me/behas" typeof="v:VCard"> <span property="v:fn">Bernhard Haslhofer</span> <span property="v:nickname">behas</span> <div rel="v:adr"> <div typeof="v:Address v:Work"> <span property="v:street-address">301 College Avenue</span> <span property="v:locality">Ithaca</span>, <span property="v:postal-code">14850</span>, <span property="v:country-name">United States</span>. </div> </div> <a rel="v:email" href="mailto:[email protected]">[email protected]</a>. </div></div>
Sample vCard Object in RDFa (see http://www.w3.org/Submission/vcard-rdf/)
Microformats vs. RDFa
<div class="vcard">
<span class="fn">Bernhard Haslhofer</span>
<div class="adr"><div class="street-address">301 College Avenue</div><span class="locality">Ithaca</span><span class="postal-code">14850</span><span class="country-name">United States</span>
</div>
<a class="email" href="mailto:[email protected]">[email protected]</a>
</div>
hCard sample created with http://microformats.org/code/hcard/creator
Also see: http://evan.prodromou.name/RDFa_vs_microformats
Microformats RDFa
flat namespace XML namespaces
support HTML4, XHTML 1.1, and HTML 5 support for XHTML 1.1
use latent HTML attributes introduces new metadata attributes
vocabulary defined by one organization/community open to any RDF-based vocabulary
Microdata (HTML5)
• A very young HTML 5 proposition that extends Microformats and addresses its shortcomings
• Items are created within an itemscope
• Ever item is assigned an arbitrary number of properties (itemprop)
• Uses global identifiers for typing and naming items
Microdata Example
<div itemscope itemtype="http://data-vocabulary.org/Person">
<span itemprop="name">Bernhard Haslhofer</span>, <span itemprop="nickname">behas</span>.
<div itemprop="address" itemscope itemtype="http://data-vocabulary.org/Address"><span itemprop="street-address">301 College Avenue</span><span itemprop="locality">Ithaca</span><span itemprop="country-name">United States</span>
</div>
</div>
Search engines and machine-readable data
Google Rich Snippets
• Reviews
• People
• Products
• Businesses and organizations
• Recipes
• Events
Google Rich Snippets
<div>L’Amourita PizzaReviewed by Ulysses Grant on Jan 6.Delicious, tasty pizza on Eastlake!L'Amourita serves up traditional wood-fired Neapolitan-style pizza, brought to your table promptly and without fuss. An ideal neighborhood pizza joint.Rating: 4.5</div>
HTML
Google Rich Snippets
<div> <div itemscope itemtype="http://data-vocabulary.org/Review"> <span itemprop="itemreviewed">L’Amourita Pizza</span> Reviewed by <span itemprop="reviewer">Ulysses Grant</span> on <time itemprop="dtreviewed" datetime="2009-01-06">Jan 6</time>. <span itemprop="summary">Delicious, tasty pizza in Eastlake!</span> <span itemprop="description">L'Amourita serves up traditional wood-fired Neapolitan-style pizza, brought to your table promptly and without fuss. An ideal neighborhood pizza joint.</span> Rating: <span itemprop="rating">4.5</span> </div></div>
Microdata
Google Rich Snippets
<div class="hreview"> <span class="item"> <span class="fn">L’Amourita Pizza</span> </span> Reviewed by <span class="reviewer">Ulysses Grant</span> on <span class="dtreviewed"> Jan 6<span class="value-title" title="2009-01-06"></span> </span>. <span class="summary">Delicious, tasty pizza on Eastlake!</span> <span class="description">L'Amourita serves up traditional wood-fired Neapolitan-style pizza, brought to your table promptly and without fuss. An ideal neighborhood pizza joint.</span> Rating: <span class="rating">4.5</span></div>
Microformats
Google Rich Snippets
<div xmlns:v="http://rdf.data-vocabulary.org/#" typeof="v:Review"> <span property="v:itemreviewed">L’Amourita Pizza</span> Reviewed by <span property="v:reviewer">Ulysses Grant</span> on <span property="v:dtreviewed" content="2009-01-06">Jan 6</span>. <span property="v:summary">Delicious, tasty pizza on Eastlake!</span> <span property="v:description">L'Amourita serves up traditional wood-fired Neapolitan-style pizza, brought to your table promptly and without fuss. An ideal neighborhood pizza joint.</span> Rating: <span property="v:rating">4.5</span></div>
RDFa
Facebook Graph API & Open Graph Protocol
Readings
Required Reading
• SKOS Primer: http://www.w3.org/TR/skos-primer/
• RDFa Primer: Bridging the Human and Data Webs.http://www.w3.org/TR/xhtml-rdfa-primer/
• HTML Microdata: http://www.w3.org/TR/microdata/
• Microformats: http://microformats.org/
Recommended Readings
• SKOS Vocabularies Overview:
• RDFa.info: http://rdfa.info/wiki/RDFa_Wiki
• CC REL: Creative Commons Rights Expression Language (CC REL)
source: http://upload.wikimedia.org/wikipedia/commons/a/a7/Wollmilchsau.png
~2000 2011
Reality
Dream
HTML 5Microdata
RDFa